Medical Radiology - Lazar A.P. 2008

Radiation Therapy
The Nature of Ionizing Radiation

All types of radiation used in medical radiology are divided into two major groups: non-ionizing and ionizing. Non-ionizing radiation includes thermal (infrared) and radiofrequency radiation. Ultrasound waves, which represent mechanical vibrations of a medium, are also classified as non-ionizing.

Ionizing radiation is any radiation whose interaction with matter results in The formation of electric charges of opposite signs. Daylight, ultraviolet, and infrared rays are low-energy and therefore are not classified as ionizing, although they can ionize a photographic emulsion.

Ionizing radiation can be corpuscular or photonic. Corpuscular radiation consists of a stream of small particles (corpuscles), while photonic radiation consists of quanta of electromagnetic waves (photons). Corpuscular radiation includes alpha radiation (a) (helium atomic nuclei), beta radiation (electrons e- and positrons e+), protons (p+), neutrons (n°), and others (over 200 varieties). Photonic radiation includes y- and X- (X-ray) rays. Gamma radiation is high-frequency, short-wavelength (10-10-10-13 m) electromagnetic radiation produced during nuclear transformations. X-rays are also a type of short-wavelength (10-9-10-12 m) electromagnetic radiation generated in vacuum cathode-ray tubes when electrons are decelerated by the anode.



Last update: 08/08/2026

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